1. Field of the Invention
The present invention relates to ladder assemblies. More particularly, the present invention the relates to shoe bracket assemblies that are used at the bottom of the rail of ladder so as to securely position the ladder with respect to an underlying surface.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Ladders are conventionally utilized to provide a user thereof with improved access to elevated locations that might otherwise be inaccessible. Ladders come in many shapes and sizes, such as straight ladders, straight extension ladders, stepladders, and combination step and extension ladders.
Ladders known as straight ladders or straight extension ladders are ladders that are conventionally positioned against an elevated surface, such as a wall or the edge of a roof, to support the ladder at a desired angle. A user then ascends the ladder to obtain access to an elevated area, such as access to an upper area of the wall or access to the roof. Straight ladders and straight extension ladders are referred to as being “straight” because their rails are typically straight and generally parallel to one another throughout the length of the ladder. A pair of feet or pads, one being coupled to the bottom of each rail, are conventionally used to engage the ground, a floor or some other supporting surface.
A ladder foot commonly comprises a U-shaped shoe pivotally coupled by a pin to the bottom of a rail of a ladder in a manner whereby the shoe is angularly adjustable between flat, toe-down and intermediate positions. In the flat position, the bottom of the shoe rests on the ground or other footing to provide maximum adhesion to smooth flat surfaces, such as asphalt, wood, concrete, etc. In the toe-down position, the shoe is tilted to have its front part contact the ground and serve as a pick-like device to provide maximum penetration and holding power on ice or hard, soft, sandy, or frozen earth.
In the past, it has been a common practice for the shoe of a ladder foot to be coupled to a rail of the ladder by a pin-and-slot coupling wherein the pin is passed laterally through a hole in the rail to be translationally fixed in relation thereto, and wherein the pin has opposite ends projecting out from laterally opposite sides of the ladder rail, and those opposite ends of the pin are received in two slots respectively formed in the two sidewalls of the U-shaped shoe.
A ladder foot of such construction has, however, a number of disadvantages for use in present day ladders. In order to provide ladders that are inexpensive, light in weight, and durable, the rails thereof are often in the form of lengths of fiberglass of U-shape in cross section so as to have a central, longitudinal elongated relatively thin web and, also, two longitudinally elongated side flanges projecting out in the same direction from the opposite sides of the web. Such rails do not lend themselves readily to a pin-and-slot coupling of a shoe to the rail wherein the two slots are in the shoe and the pin passes through a hole in the web of the rail to be translationally fixed in relation thereto. That is so, because, in view of the thinness of the fiberglass web, it would be difficult to maintain the bolt fixed in its normal alignment to the web and, because of the web thinness and the lack of mechanical strength of the fiberglass web, the transmission of half the weight of the ladder and its occupant from the web to the pin would create undue stresses in the region of the web near the pin.
In another consideration, the provision of pivotally mounting the shoe to the ladder rail by a pin-and-slot coupling wherein slots are formed in the sidewalls of the shoe has the disadvantage that the slots take up substantial space in the shoe's sidewalls in which the slots must be surrounded with a sufficient thickness of sidewall material throughout the length of the slot to withstand the mechanical strain imposed on each sidewall when the shoe is bearing substantial weights. This means, however, that each of the sidewalls of the shoe must be larger in dimension than is really necessary.
In the past, various patent have issued relating to ladder shoes and ladder shoe bracket assemblies. An early patent is that of U.S. Pat. No. 2,449,609, issued on Sep. 21, 1948 to O. A. Linder. This patent shows a rectangular plate secured of the lower leg of the ladder. Vertical flanges border the plate. A U-shaped member is slidably mounted within the flanges. A resilient means retains the sliding member upwardly retracted between the flanges. A bracket is secured to the sliding member. A T-shaped member is carried by the bracket such that the leg of the T is in an outwardly extended position. A cylindrical tube is secured to the sliding member. A ground engaging foot is resiliently carried within the tube. The T-leg is adapted to be lowered and locked against the resilient means to position the foot in an extended ground-engaging position.
U.S. Pat. No. 2,691,479, issued on Oct. 12, 1954 to J. E. Sharp, describes a ladder shoe. This ladder shoe is adapted to be pivotally and shiftably attached to the base of ladder rail upon a bolt projecting through the ladder rail above its base edge. The bottom carries an anti-slip tread on its underside and a spike at one end thereof. A pair of parallel side walls upstanding from the bottom and spaced apart sufficiently receive the ladder rail base therebetween. Relatively aligned apertures in the side walls allow the attaching bolt to extend therethrough. The apertures are elongated to permit shifting of the shoe upon the bolt.
U.S. Pat. No. 3,456,757, issued on Jul. 22, 1969 to B. S. Sain, describes a ladder stabilizer boot. The ladder legs are securely deposited in adjustable sleeve or channel. The sleeve is swivelly mounted on the boot along various angles. The boot has a base formed with a horizontal flange which is provided with ground-gripping means including holes through which anchoring pins may be driven. The sleeve is adapted to receive the ladder leg and is provided with bolts to penetrate holes in the ladder legs so as to secure it firmly to the sleeve.
U.S. Pat. No. 4,415,062, issued on Nov. 15, 1983 to J. L. Shaw, discloses a ladder foot having a bracket attached at its upper end to a ladder rail and includes a stud extending downwardly from this end. A shoe has a central sole plate and a pair of upper plates extending from the sole plate to straddle opposite sides of the bracket. A pin is fixedly secured with the upper plates and passes from one to the other through the bracket adjacent the front side of the stud. The downward extent of the stud includes an upper range within which the stud fits between the pin and sole plate in such manner that the shoe is locked in toe-down position. There are portions integrally joined with the stud so as to serve as stops for the pin.
U.S. Pat. No. 5,154,255, issued on Oct. 13, 1992 to Kiska et al., teaches a ladder shoe and method of use. The ladder shoe has a shoe body having a first side plate, a second side plate and a base. The first side plate and the second side plate are attached to the base. The side plates include curved slots through which a fastener is disposed and which movably connects the ladder shoe to the end of the side rail of the ladder. This allows the ladder shoe to move between a first position where the base is at a first angle with respect to the side rail and a second position where the base is at a second angle with respect to the side rail. Each slot has a notch in which the fastener catches causing the shoe to be maintained in an intermediate position until the shoe body is desired to be placed into another position. The base has a bottom which provides a slip-resistant surface for engaging the shoe body to essentially flat surfaces when the shoe body is in the first position.
U.S. Pat. No. 5,370,203, issued on Dec. 6, 1994 to S. A. Kiska, shows a ladder shoe spur plate. The ladder shoe has a base. This base has an elongate portion having a first side and a second side, a first edge and a second edge, and a top face and a bottom face. The top face is attached to the ladder rail attachment portion. The base has a foot pad. The base includes of a blade portion extending from the first edge. The base has a first flange portion extending from the bottom face and integrally connected thereto. There is also a second flange portion extending from the bottom face and integrally connected thereto. The base further includes a third flange portion extending from the bottom face and integrally connected thereto. A fourth flange portion extends from the bottom face and is also integrally connected thereto. The first, second, third and fourth flange portions form a pocket in which the footpad is held along the bottom face and sides of the footpad.
It is an object of the present invention to provide a shoe bracket assembly that can be preassembled prior to attachment to the ladder.
It is another object of the present invention to provide a shoe bracket assembly that is securely retained at the end of the ladder rail.
It is another object of the present invention to provide a shoe bracket assembly that is easy to repair or replace.
It is another object of the present invention to provide a shoe bracket assembly that provides stronger support to the fragile bottom ends of the ladder rails.
It is still a further object of the present invention to provide a shoe bracket assembly that allows the ladder rail to be securely positioned upon an underlying surface.
It is another object of the present invention to provide a shoe bracket assembly that properly guides the end of the rail into a properly seated position.
It is still a further object of the present invention to provide a shoe bracket assembly that simplifies assembly of the shoe bracket of the ladder.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.